docs: def get_avg_price_fifo(self) -> Decimal:
          """
          Calculates the average price paid for the security.
          security = Commodity
          Returns Decimal value.
          """
          balance = self.get_quantity()
          if not balance:
              return Decimal(0)
  
          paid = Decimal(0)
          accounts = self.get_holding_accounts()
          # get unused splits (quantity and total paid) per account.
          for account in accounts:
              splits = self.get_available_splits_for_account(account)
  
              for split in splits:
                  paid += split.value
  
          avg_price = paid / balance
          return avg_price